The present invention relates to a semiconductor device and a method for fabricating the semiconductor device, more specifically, a semiconductor device including a capacitor using as the dielectric film, a high-dielectric constant substance or a ferroelectric substance, and a method for fabricating the semiconductor device.
Recently, as the dielectric films of capacitors, the use of high-dielectric constant substances or ferroelectric substances is noted.
However, in simply using high-dielectric constant substances and ferroelectric substances as the dielectric films of capacitors, the oxygen in the dielectric films is often reduced with hydrogen in later steps after the dielectric films have been formed, and the capacitors cannot have often good electric characteristics. The oxygen in the dielectric films is reduced with hydrogen when the water contained in the inter-layer insulation films, etc. arrives at the capacitors, and the capacitor cannot have good electric characteristics.
As technique of preventing the deterioration of the dielectric films with the hydrogen and the water, the technique of forming an aluminum oxide film, covering the capacitor, and the technique of forming an aluminum oxide film on the inter-layer insulation films formed on the capacitors are proposed. Aluminum oxide film has the function of preventing the diffusion of hydrogen and water. Accordingly, the proposed techniques can prohibit the hydrogen and water from arriving at the dielectric film, whereby the deterioration of the dielectric film with the hydrogen and the water can be prevented. These techniques are proposed in, e.g., Patent References 1 and 2.
Following references disclose the background art of the present invention.
[Patent Reference 1]
Specification of Japanese Patent Application Unexamined Publication No. 2002-176149
[Patent Reference 2]
Specification of Japanese Patent Application Unexamined Publication No. 2003-197878
[Patent Reference 3]
Specification of Japanese Patent Application Unexamined Publication No. 2003-100994
[Patent Reference 4]
Specification of Japanese Patent No. 3114710
[Patent Reference 5]
Specification of Japanese Patent Application Unexamined Publication No. 2003-229542
However, in simply forming an aluminum oxide film, it is difficult to securely prevent the deterioration of the dielectric film with the hydrogen and the water. The deterioration of the dielectric film with the hydrogen and the water lowers the fabrication yield.